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authorMatheus Tavares Bernardino <quic_mathbern@quicinc.com>2023-05-04 12:37:31 -0300
committerTaylor Simpson <tsimpson@quicinc.com>2023-05-18 12:40:52 -0700
commit758370052fb602f9f23c3b8ae26a6133373c78e6 (patch)
tree6953d7d93c67618e73669f4b6102ebb99d10b6a4 /gdbstub/gdbstub.c
parent9e6d4938d106ca775108ec2a1fecc6d789543088 (diff)
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gdbstub: only send stop-reply packets when allowed to
GDB's remote serial protocol allows stop-reply messages to be sent by the stub either as a notification packet or as a reply to a GDB command (provided that the cmd accepts such a response). QEMU currently does not implement notification packets, so it should only send stop-replies synchronously and when requested. Nevertheless, it still issues unsolicited stop messages through gdb_vm_state_change(). Although this behavior doesn't seem to cause problems with GDB itself (the messages are just ignored), it can impact other debuggers that implement the GDB remote serial protocol, like hexagon-lldb. Let's change the gdbstub to send stop messages only as a response to a previous GDB command that accepts such a reply. Signed-off-by: Matheus Tavares Bernardino <quic_mathbern@quicinc.com> Acked-by: Alex Bennée <alex.bennee@linaro.org> Signed-off-by: Taylor Simpson <tsimpson@quicinc.com> Message-Id: <a49c0897fc22a6a7827c8dfc32aef2e1d933ec6b.1683214375.git.quic_mathbern@quicinc.com>
Diffstat (limited to 'gdbstub/gdbstub.c')
-rw-r--r--gdbstub/gdbstub.c37
1 files changed, 28 insertions, 9 deletions
diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
index 0760d78..be18568 100644
--- a/gdbstub/gdbstub.c
+++ b/gdbstub/gdbstub.c
@@ -777,6 +777,10 @@ typedef void (*GdbCmdHandler)(GArray *params, void *user_ctx);
/*
* cmd_startswith -> cmd is compared using startswith
*
+ * allow_stop_reply -> true iff the gdbstub can respond to this command with a
+ * "stop reply" packet. The list of commands that accept such response is
+ * defined at the GDB Remote Serial Protocol documentation. see:
+ * https://sourceware.org/gdb/onlinedocs/gdb/Stop-Reply-Packets.html#Stop-Reply-Packets.
*
* schema definitions:
* Each schema parameter entry consists of 2 chars,
@@ -802,6 +806,7 @@ typedef struct GdbCmdParseEntry {
const char *cmd;
bool cmd_startswith;
const char *schema;
+ bool allow_stop_reply;
} GdbCmdParseEntry;
static inline int startswith(const char *string, const char *pattern)
@@ -835,6 +840,7 @@ static int process_string_cmd(void *user_ctx, const char *data,
}
}
+ gdbserver_state.allow_stop_reply = cmd->allow_stop_reply;
cmd->handler(params, user_ctx);
return 0;
}
@@ -1283,11 +1289,14 @@ static void handle_v_attach(GArray *params, void *user_ctx)
gdbserver_state.g_cpu = cpu;
gdbserver_state.c_cpu = cpu;
- g_string_printf(gdbserver_state.str_buf, "T%02xthread:", GDB_SIGNAL_TRAP);
- gdb_append_thread_id(cpu, gdbserver_state.str_buf);
- g_string_append_c(gdbserver_state.str_buf, ';');
+ if (gdbserver_state.allow_stop_reply) {
+ g_string_printf(gdbserver_state.str_buf, "T%02xthread:", GDB_SIGNAL_TRAP);
+ gdb_append_thread_id(cpu, gdbserver_state.str_buf);
+ g_string_append_c(gdbserver_state.str_buf, ';');
+ gdbserver_state.allow_stop_reply = false;
cleanup:
- gdb_put_strbuf();
+ gdb_put_strbuf();
+ }
}
static void handle_v_kill(GArray *params, void *user_ctx)
@@ -1310,12 +1319,14 @@ static const GdbCmdParseEntry gdb_v_commands_table[] = {
.handler = handle_v_cont,
.cmd = "Cont",
.cmd_startswith = 1,
+ .allow_stop_reply = true,
.schema = "s0"
},
{
.handler = handle_v_attach,
.cmd = "Attach;",
.cmd_startswith = 1,
+ .allow_stop_reply = true,
.schema = "l0"
},
{
@@ -1698,10 +1709,13 @@ static void handle_gen_set(GArray *params, void *user_ctx)
static void handle_target_halt(GArray *params, void *user_ctx)
{
- g_string_printf(gdbserver_state.str_buf, "T%02xthread:", GDB_SIGNAL_TRAP);
- gdb_append_thread_id(gdbserver_state.c_cpu, gdbserver_state.str_buf);
- g_string_append_c(gdbserver_state.str_buf, ';');
- gdb_put_strbuf();
+ if (gdbserver_state.allow_stop_reply) {
+ g_string_printf(gdbserver_state.str_buf, "T%02xthread:", GDB_SIGNAL_TRAP);
+ gdb_append_thread_id(gdbserver_state.c_cpu, gdbserver_state.str_buf);
+ g_string_append_c(gdbserver_state.str_buf, ';');
+ gdb_put_strbuf();
+ gdbserver_state.allow_stop_reply = false;
+ }
/*
* Remove all the breakpoints when this query is issued,
* because gdb is doing an initial connect and the state
@@ -1725,7 +1739,8 @@ static int gdb_handle_packet(const char *line_buf)
static const GdbCmdParseEntry target_halted_cmd_desc = {
.handler = handle_target_halt,
.cmd = "?",
- .cmd_startswith = 1
+ .cmd_startswith = 1,
+ .allow_stop_reply = true,
};
cmd_parser = &target_halted_cmd_desc;
}
@@ -1736,6 +1751,7 @@ static int gdb_handle_packet(const char *line_buf)
.handler = handle_continue,
.cmd = "c",
.cmd_startswith = 1,
+ .allow_stop_reply = true,
.schema = "L0"
};
cmd_parser = &continue_cmd_desc;
@@ -1747,6 +1763,7 @@ static int gdb_handle_packet(const char *line_buf)
.handler = handle_cont_with_sig,
.cmd = "C",
.cmd_startswith = 1,
+ .allow_stop_reply = true,
.schema = "l0"
};
cmd_parser = &cont_with_sig_cmd_desc;
@@ -1785,6 +1802,7 @@ static int gdb_handle_packet(const char *line_buf)
.handler = handle_step,
.cmd = "s",
.cmd_startswith = 1,
+ .allow_stop_reply = true,
.schema = "L0"
};
cmd_parser = &step_cmd_desc;
@@ -1976,6 +1994,7 @@ void gdb_read_byte(uint8_t ch)
{
uint8_t reply;
+ gdbserver_state.allow_stop_reply = false;
#ifndef CONFIG_USER_ONLY
if (gdbserver_state.last_packet->len) {
/* Waiting for a response to the last packet. If we see the start